For more than six years, the underground bicycling club has prowled L.A.'s pavement at night. Some see a group high on the rude chain; others see a vehicle for activism.

It's past midnight, and a fluorescent glow settles over LAX as travelers wrestle bags down the sidewalk and shuttles dart in and out of terminals.

A gust of whirring chains and gears cuts in. Speeding onto the departure level, a pack of bicyclists fans out across open lanes. Some sit up and stretch, no hands. One rider on a fixed-gear bike puts his feet up on the frame as the pedals furiously spin on their own.

"Whoop! Whoop!" chirps one of the riders, warning of police up ahead.

Wolfpack Hustle is on the move.

The pack is one of L.A.'s most notorious underground cycling clubs. For more than six years, it has prowled the pavement at night — a high-speed middle finger aimed at L.A.'s car culture.

Red lights and cars are minor inconveniences. Potholes, broken glass and metal shards that can cut up tires? Just bring a repair kit.

Every Monday at 10 p.m., a couple dozen Wolfpack riders surge from the parking lot of Tang's Donut in Silver Lake for a journey that can carry them up to 60 miles or more.

They mix it up each week — Mt. Wilson, the Vincent Thomas Bridge, Magic Mountain. They ride at night because there's less traffic. Sometimes, they make up the route as they go. Detours, like this casual loop through LAX, are just part of the fun.

Everyone is invited: high school students, twentysomethings, working professionals in their 40s. But no one waits if you can't keep up. Some of the state's strongest road and track cyclists have ridden with the pack or raced in its events.

(Last year, a handful of riders made international news during the Carmageddon freeway closure by racing a jet from Burbank to Long Beach — and winning. And, in a sign of how the pack has been inching toward the mainstream, they say they did it without breaking any traffic laws.)

"It's the top of the food chain in underground bike street racing," says 17-year-old Kevin Molina, who lives near Dodger Stadium and started riding about two years ago. "Even though it's risky and may seem completely and utterly stupid, the Wolfpack Hustle is the only way we can truly release our anger and stress out in those streets."

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The push-as-hard-as-you-can style of Wolfpack and other L.A. street bicyclists has earned them both the adoration of a dedicated following and the rage of some motorists, who believe some cyclists trolling L.A.'s streets are out of control.

Santa Monica resident Robert J. Rausch, 65, calls many of the bicyclists who dart along L.A.'s streets rogues. He says he has narrowly escaped several crashes involving bicyclists who ran red lights.

But outrage from motorists hasn't appeared to stop the number of street cyclists from growing. Titanium, pavement and a splash of rebellion — it's a cocktail made for L.A.

The Critical Mass movement, made up of bicyclists who ride through city streets in large enough numbers to create their own traffic, was taking off in San Francisco and other cities in the early 1990s, but it took several years before the street biking movement really caught on in Los Angeles.

But over the last decade, local groups like the Midnight Ridazz have drawn thousands of cyclists to their open-invite rides. Fueled by social media, they grew so large that a few years ago the organizers stopped planning rides and instead use their website as a hub for bicyclists to start their own.

A handful of bicyclists from the Midnight Ridazz, wanting more speed, formed Wolfpack Hustle.

For years, Wolfpack's founders worked hard to keep up the group's renegade reputation. But as its numbers grew and Wolfpack found itself an unexpected vehicle for activism, they've shifted closer to the mainstream, sometimes working with authorities to make sure no one gets hurt — or a citation.

But not tonight. Whizzing through LAX, the pack keeps a steady pace while swerving past construction workers and orange cones.

They pour on the speed and exit onto Century Boulevard. The pack falls into a single-file line so riders can take turns blocking the wind.

The hustle back to Tang's is 15 more miles — and, who knows, it's a big city, and they're already talking about another detour.

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Wolfpack riders acknowledge that negotiating L.A.'s streets in the dark, zigzagging around cars and running red lights, can be a dangerous addiction.

On their way to LAX, the riders climb Sunset Boulevard in Beverly Hills, standing up on their pedals through a dark stretch illuminated by infrequent street lamps and headlights.

Ivan Therrien, a 33-year-old bike shop manager from Mar Vista, is pushing his neon-red carbon S-Works Tarmac to the limit but is caught off guard by a protruding asphalt ridge. He topples head-first into a concrete light post.

The bike survives. Therrien fractures his wrist and injureshis shoulder. He hitches a ride to the next regrouping spot at the Santa Monica Pier, hobbles back onto his bicycle and rides home.